We seek to develop a novel insulin analog to enhance the safety and efficacy of insulin pump therapy with broad application to the Artificial Pancreas Project (smart pumps). A proprietary approach is proposed based on the favorable physico-chemical properties conferred by chloro-aromatic substitutions in the insulin molecule. This Phase 2 SBIR application thus builds on progress obtain in the Phase 1 program in the characterization of 4-Cl-PheB24-KP-insulin. In this derivative of insulin lispro (the active component of Humalog; Eli Lilly and Co) the para proton of the aromatic ring of PheB24 is substituted by a larger and electronegative halogen atom. Results of Phase 1 studies established that this substitution (i) is compatible with native receptor-binding affinity and natie biological potency; (ii) leads to an accelerated rate of disassembly of the insulin hexamer in vitro; (iii) is associated with foreshortened pharmacodynamics of insulin action in euglycemic clamp studies in a pig model; and (iv) augments the resistance of insulin to physical degradation above room temperature on gentle agitation as in a pump reservoir. This unique confluence of advantageous features predicts significant clinical advantages both with respect to patient convenience and with respect to the performance of control algorithms employed in CGM-coupled closed-loop systems. Accordingly, a Phase 2 development plan is proposed in support of clinical-scale manufacture and optimization of formulation leading to I-GMP production (Aims 1-3) and formal toxicity/tolerance testing in animals in support of an IND application to the FDA (Aim 4). Achievement of these milestones will enable a future Phase 2B application in support of first-in-human trials, anticipated to be a phase 1a clamp study of healthy volunteers. The present application thus provides a logical bridge between highly promising in vitro and animal data, as generated in the Phase 1 SBIR program, and key pre-IND milestones.